Intercalated layered silicate

ABSTRACT

An intercalated layered silicate comprises a layered silicate and an intercalating agent sorbed between the silicate layers of the layered silicate. The amount of intercalating agent is effective to provide an average interlayer spacing between the silicate layers of at least about 20 Å. The intercalating agent has a formula selected from formulas I through VII described herein. The intercalated layered silicate may be exfoliated by mixing it with a matrix medium and adding sufficient energy to form a dispersed-particle composition. A packaging film, such as a food packaging film, may comprise the dispersed-particle composition.

BACKGROUND OF THE INVENTION

The present invention relates to intercalated layered silicates and todispersed-particle compositions comprising silicate platelets exfoliatedfrom intercalated layered silicates.

Intercalated clays may be made using a quaternary ammonium-basedintercalating agent. However, it may be difficult to obtain governmentagency approval to utilize quaternary ammonium-based intercalatingagents in some end-use applications, such as food-contacting materials.Further, quaternary ammonium-based intercalating agents may show anunacceptably high amount of decomposition at the processing residenttimes and temperatures desired for processing a matrix mediumincorporating the quaternary ammonium-based intercalating agent.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention may address one or moreof the aforementioned problems.

An intercalated layered silicate comprises a layered silicate and anintercalating agent sorbed between the silicate layers of the layeredsilicate. The amount of intercalating agent is effective to provide anaverage interlayer spacing between the silicate layers of at least about20 Å. The intercalating agent has a formula selected from formulas Ithrough VII as described below.

The intercalated layered silicate may be exfoliated by mixing it with amatrix medium and adding sufficient energy to form a dispersed-particlecomposition. A packaging film, such as a food packaging film, maycomprise the dispersed-particle composition.

These and other objects, advantages, and features of the invention willbe more readily understood and appreciated by reference to the detaileddescription of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an X-ray diffraction pattern for montmorillonite clayintercalated with pentaerythritol monostearate, as discussed in Example1;

FIG. 2 is an X-ray diffraction pattern for non-intercalatedmontmorillonite clay;

FIG. 3 is an X-ray diffraction pattern for montmorillonite clayintercalated with dimethyl didehydrogenated tallow quaternary ammoniumintercalated montmorillonite, as discussed in Comparative 1;

FIG. 4 is an X-ray diffraction pattern for montmorillonite clayintercalated with pentaerythritol monostearate dispersed in a matrixmedium of linear low density polyethylene, as discussed in Example 3;

FIG. 5 is an X-ray diffraction pattern for montmorillonite clayintercalated with pentaerythritol monostearate dispersed in a matrixmedium of isotactic polypropylene, as discussed in Example 4;

FIG. 6 is an X-ray diffraction pattern for montmorillonite clayintercalated with pentaerythritol monostearate dispersed in a matrixmedium of ethylene/vinyl acetate copolymer, as discussed in Example 5;

FIG. 7 is an X-ray diffraction pattern for montmorillonite clayintercalated with pentaerythritol monostearate dispersed in a matrixmedium of nylon-6 polymer, as discussed in Example 6;

FIG. 8 is a thermogravimetric analysis (TGA) graph for the Example 1PEMS intercalated montmorillonite clay; and

FIG. 9 is a thermogravimetric analysis (TGA) graph obtained for theComparative Sample 1 Cloisite 20A intercalated clay.

DETAILED DESCRIPTION OF THE INVENTION

An intercalated layered silicate comprises a layered silicate comprisinga plurality of silicate layers. An intercalating agent is sorbed betweenthe silicate layers in an amount effective to provide an averageinterlayer spacing between the silicate layers of at least about 20 Å.

Layered Silicate

The intercalated layered silicate comprises a layered silicate. Thelayered silicate (i.e., phyllosilicate) may be naturally occurring orsynthetically derived. Exemplary layered silicates include:

1. Natural clays such as smectite clays, for example, bentonite clays(e.g., montmorillonite, hectorite), mica, vermiculite, nontronite,beidellite, volkonskoite, and saponite;

2. Layered polysilicates (e.g., layered silicic acid), such as kanemite,makatite, ilerite, octosilicate, magadiite, and kenyaite; and

3. Synthetic clays, such as, synthetic silicates, synthetic mica,synthetic saponite, synthetic laponite, and synthetic hectorite.

Layered silicates comprise a plurality of silicate layers, that is, alaminar structure having a plurality of stacked silicate sheets orlayers with a variable interlayer distance between the layers. Forexample, the layered silicate may have a 2:1 layer structure typified byan octahedral layer, comprising aluminum or magnesium, sandwichedbetween two tetrahedral silicate layers. The layers of the layeredsilicate may be turbostratic relative to each other, such that thelayered silicate may be swellable, for example, in water. The averagethickness of the silicate layers may be at least about any of thefollowing: 3, 5, 8, 10, 15, 20, 30, 40, and 50 Å; and at most about anyof the following: 60, 50, 45, 35, 25, 20, 15, 12, 10, 8, and 5 Å. Forexample, many layered silicates have a silicate layer thickness rangingfrom 8 to 11 Å.

The average interlayer spacing of the layered silicate at 60% relativehumidity before intercalation with the intercalating agent may be atleast about any of the following: 1, 2, 3, 4, 5, 6, 8, and 10 Å; and maybe at most about any of the following: 20, 15, 10, 8, 6, 5, 3, and 2 Å.

The average interlayer spacing (i.e., the gallery spacing) of a layeredsilicate (including an intercalated layered silicate) refers to thedistance between the internal faces of the non-exfoliated, adjacentlayers of representative samples of the layered silicate. The interlayerspacing may be calculated using standard powder wide angle X-raydiffraction techniques generally accepted in the art in combination withBragg's law equation, as is known in the art.

Useful layered silicates are available from various companies includingNanocor, Inc., Southern Clay Products, Kunimine Industries, Ltd., andRheox.

Intercalating Agent

The intercalated layered silicate comprises an intercalating agentsorbed between the silicate layers of the layered silicate. The term“sorbed” in this context means inclusion within the layered silicate(for example, by adsorption and/or absorption) without covalent bonding.An intercalating agent that is sorbed between silicate layers may beheld to the interlayer surface of a silicate layer by one or more ofionic complexing, electrostatic complexing, chelation, hydrogen bonding,ion-dipole interaction, dipole-dipole interaction, and van der Waalsforces.

The intercalating agent may have any one or more of the followingformulas:

R⁴ may represent an acyl group, for example, an acyl group having atleast any of 8, 10, 12, 14, and 16 carbon atoms; and/or at most any of30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and 10 carbon atoms. The acylgroup may be branched or unbranched. The acyl group may be saturated orunsaturated (for example, with any of one, two, three, or at least fourunits of unsaturation);

R⁴ may represent an alkyl group, for example, an alkyl group having atleast any of 8, 10, 12, 14, and 16 carbon atoms; and/or at most any of30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and 10 carbon atoms. The alkylgroup may be branched or unbranched;

R⁴ may represent an alkenyl group, for example, an alkenyl group havingat least any of 8, 10, 12, 14, and 16 carbon atoms; and/or at most anyof 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and 10 carbon atoms. Thealkenyl group may be branched or unbranched;

R⁴ may represent an alkadienyl group, for example, an alkadienyl grouphaving at least any of 8, 10, 12, 14, and 16 carbon atoms; and/or atmost any of 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and 10 carbon atoms.The alkadienyl group may be branched or unbranched.

R⁴ may represent a carbon chain group (branched or unbranched), forexample having at least any of 8, 10, 12, 14, and 16 carbon atoms;and/or at most any of 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, and 10carbon atoms, where the carbon chain group incorporates one or morependant or terminal groups selected from each of a hydroxyl group, acarboxyl group, an epoxy group, an isocyanate group, an aryl group(e.g., a phenyl group or a tolyl group), and an arylmethyl group havingthe formula

“Ar” represents an aryl group. R⁶ and R⁷ may each independentlyrepresent a hydrogen, an acyl group, an alkyl group, or an alkenylgroup.

R⁵ may represent any of H, —CH₃, —CH₂CH₃, and any of the groupsrepresented by R⁴.

R⁸ may represent oxylated groups selected from any one or more of thefollowing formulas:

In the above formulas, “n” may be at least any of the following values:2, 4, 5, 6, 8, 10 and/or at most any of the following values: 6, 8, 10,12; for example, “n” may range from 4 to 12. In the above formulas, “x”may be at least any of the following values: 4, 5, 6, 8, 10 and/or atmost any of the following values: 6, 8, 10, 12, 13, 14; for example, “x”may range from 5 to 13.

R¹, R² and R³ may each independently represent any of H, —CH₃, —CH₂CH₃,

and any of the groups represented by R⁴ and R⁸, provided that any oftwo, at least two, or three of R¹, R², and R³ may be H.

A branch R⁴ group may lack any branches (i.e., pendent groups) havingmore than two carbons (e.g., ethyl group) or more than one carbon (e.g.,methyl group).

The R⁴ group may be compatible with the matrix medium of expected use.In this sense, the R⁴ group of the intercalating agent may facilitatethe dispersion in the matrix medium of the silicate platelets havingsorbed intercalating agent, such that a colloidal dispersion may beformed where the platelets do not settle out of the matrix medium.

Exemplary intercalating agents having the formula I above include fattyacid esters of pentaerythritol (i.e., fatty acid esters of2,2-bis-hydroxymethyl-1,3-propanediol), for example, pentaerythritolmonostearate (“PEMS”), pentaerythritol monobehenate, pentaerythritolmonooleate, pentaerythritol ricinoleate, and pentaerythritolmonolaurate. Other exemplary intercalating agents having the formula Iabove are pentaerythityl stearol (i.e.,2-(hydroxymethyl)-2-[(octadecyloxy)methyl]-1,3-propanediol);2-(hydroxymethyl)-2-[(4-cyclo-hexanebutyrate)methyl]-1,3-propanediol;and 2-(hydroxymethyl)-2-[(4-phenylbutyrate)methyl]-1,3-propanediol.

Exemplary intercalating agents having the formula II above include1-hydroxy-2,2-bis(hydroxymethyl)octadecane;1-hydroxy-2,2-bis(hydroxymethyl)tetradecane; and1-hydroxy-2,2-bis(hydroxymethyl)dodecane. Exemplary intercalating agentshaving the formula III above include2-(hydroxymethyl)-2-[(octadecylamino)methyl]-1,3-propanediol. Exemplaryintercalating agents having the formula IV above include2-(hydroxymethyl)-2-[(octadecylthio)methyl]-1,3-propanediol. Exemplaryintercalating agents having the formula V above include2-(hydroxymethyl)-2-[(14-hydroxy-3,6,9,12-tetraoxadeacanoyl)methyl]-1,3-propandiol.

Exemplary intercalating agents having the formula VI above includesteroyl citric acid, 2-(octadecanoxy)-1,2,3-propanetricaboxylic acid,2-(4-phenylbutanoxy)-1,2,3-propanetricaboxylic acid, and stearylcitrate.

Suitable methods for the synthesis of compounds having the aboveformulas are known to those of skill in the art, and may be found, forexample, in Advanced Organic Chemistry, 3^(rd) Ed., Jerry March, JohnWiley & Sons, New York, 1985, which is incorporated herein in itsentirety by reference.

The intercalating agent may be a nonionic intercalating agent, that is,an intercalating agent that does not tend to form or exchange ions, forexample, in intercalating a layered silicate.

The average interlayer spacing between the silicate layers of theintercalated layered silicate may be at least about any of thefollowing: 20, 30, 40, 50, 60, 70, 80, and 90 Å; and/or may be at mostabout any of the following: 100, 90, 80, 70, 60, 50, 40, 30, 25 Å. Theamount of intercalating agent sorbed between the silicate layers may beeffective to provide any of the forgoing average interlayer spacingbetween the silicate layers. The measurement of the average interlayerspacing of the intercalated layered silicate may be made at a relativehumidity of 60%.

The amount of intercalating agent sorbed in the intercalated layeredsilicate per 100 weight parts layered silicate may be at least aboutand/or at most about any of the following: 5, 10, 20, 30, 50, 70, 90,110, 150, 200, and 300 weight parts.

The intercalated layered silicate may be essentially free ofintercalating agent comprising onium functionality. The intercalatedsilicate may be essentially free of any one, or of all, or of anycombination of the following compounds: ammonium compounds, quaternaryammonium compounds, tertiary ammonium compounds, secondary ammoniumcompounds, primary ammonium compounds, phosponium compounds, quaternaryphosponium compounds, tertiary phosponium compounds, secondaryphosponium compounds, primary phosponium compounds, arsonium compounds,stibonium compounds, oxonium compounds, and sulfonium compounds.

Exemplary ammonium compounds from which the intercalated layeredsilicate may be essentially free include any one or any combination ofthe following: alkyl ammonium compounds, such as tetramethyl ammoniumcompounds, hexyl ammonium compounds, butyl ammonium compounds,bis(2-hydroxyethyl)dimethyl ammonium compounds,bis(2-hydroxyethyl)octadecyl methyl ammonium compounds, octadecyltrimethyl ammonium compounds, octadecyl benzyl dimethyl ammoniumcompounds, hexyl benzyl dimethyl ammonium compounds, benzyl trimethylammonium compounds, butyl benzyl dimethyl ammonium compounds, tetrabutylammonium compounds, dodecyl ammonium compounds,di(2-hydroxyethyl)ammonium compounds, and polyalkoxylated ammoniumcompounds.

Exemplary phosphonium compounds from which the intercalated layeredsilicate may be essentially free include any one or any combination ofthe following: alkyl phosphonium compounds, such as tetrabutylphosphonium compounds, trioctyl octadecyl phosphonium compounds,tetraoctyl phosphonium compounds, octadecyl triphenyl phosphoniumcompounds.

The intercalated layered silicate may be essentially free of anyintercalating agent comprising a compound selected from any or all ofthe compounds listed in the previous three paragraphs.

Manufacture of the Intercalated Layered Silicate

To make the intercalated layered silicate, a layered silicate is mixedwith the intercalating agent to effect the inclusion (i.e., sorption) ofthe intercalating agent in the interlayer space between the silicatelayers of the layered silicate. In doing so, the resulting intercalatedlayered silicate may be rendered organophilic (i.e., hydrophobic) andshow an enhanced attraction to an organic matrix medium.

In making the intercalated layered silicate, the intercalating agent mayfirst be mixed with a carrier, for example, a carrier comprising one ormore solvents such as water and/or organic solvents such as ethanol todisperse or solubilize the intercalating agent in the carrier. Theintercalating agent/carrier blend may subsequently be mixed with thelayered silicate. Alternatively, the layered silicate may be mixed withthe carrier to form a slurry, to which the intercalating agent may beadded. Also, the intercalating agent may be mixed directly with thelayered silicate without the benefit of a carrier. Intercalation may beenhanced by addition of one or more of heat, pressure, high shearmixing, ultrasonic cavitation, and microwave radiation to any of theabove systems.

The inclusion of the intercalation agent within the interlayer spacesbetween the silicate layers of the layered silicate increases theinterlayer spacing between adjacent silicate layers. This may disruptthe tactoid structure of the layered silicate to enhance thedispersibility of the intercalated layered silicate in the matrixmedium, as discussed below.

The intercalating agent sorbed between the silicate layers may be anamount and/or type effective to increase the interlayer spacing betweenthe silicate layers—relative to the spacing before the sorption of theintercalating agent—by at least about any of the following: 5, 6, 7, 8,10, 12, 14, 15, 18, 20, 30, 40, 50, 60, 70, 80, and 90 Å; and/or by atmost about any of the following: 100, 90, 80, 70, 60, 50, 40, 30, 25,20, 18, 15, 12, 10, 8, and 7 Å.

The intercalated layered silicate may be further treated to aiddispersion and/or exfoliation in a matrix medium and/or improve thestrength of a resulting polymer/silicate interface. For example, theintercalated layered silicate may be treated with a surfactant toenhance compatibility with the matrix medium. Also by way of example,the intercalated layered silicate may be further intercalated with acompatibilizer, such as a polyolefin oligomer having polar groups. Anexample is maleic anhydride modified olefin oligomer or maleic anhydridemodified ethylene vinyl acetate oligomer. An oligomer may be modified(e.g., grafted) with unsaturated carboxylic acid anhydride (i.e.,anhydride-modified oligomer) to incorporate anhydride functionality,which promotes or enhances the adhesion characteristics of the oligomer.Examples of unsaturated carboxylic acid anhydrides include maleicanhydride, fumaric anhydride, and unsaturated fused ring carboxylic acidanhydrides. Anhydride-modified polymer may be made by grafting orcopolymerization, as is known in the art. Useful anhydride-modifiedoligomers may contain anhydride group in an amount (based on the weightof the modified polymer) of at least about any of the following: 0.1%,0.5%, 1%, and 2%; and/or at most about any of the following: 10%, 7.5%,5%, and 4%.

The intercalated layered silicate may have a peak degradationtemperature of at least about any of the following: 360, 380, 390, 395,400, 405, 410, 420, 430, and 440° C.; and/or at most about any of thefollowing: 380, 390, 395, 400, 405, 410, 420, 430, 440, and 450° C. Theintercalated layered silicate may have an onset temperature ofdegradation of at least about any of the following: 200, 210, 220, 230,240, 250, and 280° C.; and/or at most about any of the following: 220,230, 240, 250, 280, and 300° C. The peak degradation temperature andonset temperature of degradation may be determined by thermogravimetricanalysis (TGA) of the sample operating at a 20° C. per minute scan ratefrom room temperature to 800° C. in an argon purged atmosphere, andutilizing first derivative of weight loss analysis. A useful TGA machinefor such analysis is the TGA Q50 model available from TA Instruments,Inc.

Dispersed-Particle Composition

The intercalated layered silicate may be exfoliated to form adispersed-particle composition comprising a plurality of dispersedparticles comprising exfoliated silicate platelets dispersed within amatrix medium. The dispersed particles may comprise silicate plateletshaving sorbed intercalating agent of the type previously discussed.

The matrix medium may comprise one or more polymers, for example, one ormore thermoplastic polymers, such as one or more polymers selected frompolyolefin, ethylene/vinyl alcohol copolymer, ionomer, vinyl plastic,polyamide, polyester, and polystyrene.

The matrix medium may comprise one or more energy curable polymerprecursors, for example, one or more energy curable precursors selectedfrom multifunctional acrylates or methacrylates, thiol-ene systems,epoxy/amine or epoxy polyol systems, and polyurethane precursors such asisocyanates and polyols.

The matrix medium may comprise one or more compounds useful in theformulation of paints, coatings, varnishes, greases, cosmetics, orpharmaceutical excipients (either topical or internal).

Polyolefins

The matrix medium may comprise one or more polyolefins. Exemplarypolyolefins include ethylene homo- and co-polymers and propylene homo-and co-polymers. The term “polyolefins” includes copolymers that containat least 50 mole % monomer units derived from olefin. Ethylenehomopolymers include high-density polyethylene (“HDPE”) and low densitypolyethylene (“LDPE”). Ethylene copolymers include ethylene/alpha-olefincopolymers (“EAOs”), ethylene/unsaturated ester copolymers, andethylene/(meth)acrylic acid. (“Copolymer” as used in this applicationmeans a polymer derived from two or more types of monomers, and includesterpolymers, etc.)

EAOs are copolymers of ethylene and one or more alpha-olefins, thecopolymer having ethylene as the majority mole-percentage content. Thecomonomer may include one or more C₃-C₂₀ α-olefins, one or more C₄-C₁₂α-olefins, and one or more C₄-C₈ α-olefins. Useful α-olefins include1-butene, 1-hexene, 1-octene, and mixtures thereof.

Exemplary EAOs include one or more of the following: 1) medium densitypolyethylene (“MDPE”), for example having a density of from 0.926 to0.94 g/cm3; 2) linear medium density polyethylene (“LMDPE”), for examplehaving a density of from 0.926 to 0.94 g/cm3; 3) linear low densitypolyethylene (“LLDPE”), for example having a density of from 0.915 to0.930 g/cm3; 4) very-low or ultra-low density polyethylene (“VLDPE” and“ULDPE”), for example having density below 0.915 g/cm3, and 5)homogeneous EAOs. Useful EAOs include those having a density of lessthan about any of the following: 0.925, 0.922, 0.92, 0.917, 0.915,0.912, 0.91, 0.907, 0.905, 0.903, 0.9, and 0.898 grams/cubic centimeter.Unless otherwise indicated, all densities herein are measured accordingto ASTM DI 505.

The polyethylene polymers may be either heterogeneous or homogeneous. Asis known in the art, heterogeneous polymers have a relatively widevariation in molecular weight and composition distribution.Heterogeneous polymers may be prepared with, for example, conventionalZiegler-Natta catalysts.

On the other hand, homogeneous polymers are typically prepared usingmetallocene or other single-site catalysts. Such single-site catalyststypically have only one type of catalytic site, which is believed to bethe basis for the homogeneity of the polymers resulting from thepolymerization. Homogeneous polymers are structurally different fromheterogeneous polymers in that homogeneous polymers exhibit a relativelyeven sequencing of comonomers within a chain, a mirroring of sequencedistribution in all chains, and a similarity of length of all chains. Asa result, homogeneous polymers have relatively narrow molecular weightand composition distributions. Examples of homogeneous polymers includethe metallocene-catalyzed linear homogeneous ethylene/alpha-olefincopolymer resins available from the Exxon Chemical Company (Baytown,Tex.) under the EXACT trademark, linear homogeneousethylene/alpha-olefin copolymer resins available from the MitsuiPetrochemical Corporation under the TAFMER trademark, and long-chainbranched, metallocene-catalyzed homogeneous ethylene/alpha-olefincopolymer resins available from the Dow Chemical Company under theAFFINITY trademark.

Another exemplary ethylene copolymer is ethylene/unsaturated estercopolymer, which is the copolymer of ethylene and one or moreunsaturated ester monomers. Useful unsaturated esters include: 1) vinylesters of aliphatic carboxylic acids, where the esters have from 4 to 12carbon atoms, and 2) alkyl esters of acrylic or methacrylic acid(collectively, “alkyl(meth)acrylate”), where the esters have from 4 to12 carbon atoms.

Representative examples of the first (“vinyl ester”) group of monomersinclude vinyl acetate, vinyl propionate, vinyl hexanoate, and vinyl2-ethylhexanoate. The vinyl ester monomer may have from 4 to 8 carbonatoms, from 4 to 6 carbon atoms, from 4 to 5 carbon atoms, andpreferably 4 carbon atoms.

Representative examples of the second (“alkyl(meth)acrylate”) group ofmonomers include methyl acrylate, ethyl acrylate, isobutyl acrylate,n-butyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate, methylmethacrylate, ethyl methacrylate, isobutyl methacrylate, n-butylmethacrylate, hexyl methacrylate, and 2-ethylhexyl methacrylate. Thealkyl(meth)acrylate monomer may have from 4 to 8 carbon atoms, from 4 to6 carbon atoms, and preferably from 4 to 5 carbon atoms.

The unsaturated ester (i.e., vinyl ester or alkyl(meth)acrylate)comonomer content of the ethylene/unsaturated estercopolymer may range from about 6 to about 18 weight %, and from about 8to about 12 weight %, based on the weight of the copolymer. Usefulethylene contents of the ethylene/unsaturated ester copolymer includethe following amounts: at least about 82 weight %, at least about 85weight %, at least about 88 weight %, no greater than about 94 weight %,no greater than about 93 weight %, and no greater than about 92 weight%, based on the weight of the copolymer.

Representative examples of ethylene/unsaturated ester copolymers includeethylene/methyl acrylate, ethylene/methyl methacrylate, ethylene/ethylacrylate, ethylene/ethyl methacrylate, ethylene/butyl acrylate,ethylene/2-ethylhexyl methacrylate, and ethylene/vinyl acetate.

Another useful ethylene copolymer is ethylene/(meth)acrylic acid, whichis the copolymer of ethylene and acrylic acid, methacrylic acid, orboth.

Useful propylene copolymer includes: 1) propylene/ethylene copolymers(“EPC”), which are copolymers of propylene and ethylene having amajority weight % content of propylene, such as those having an ethylenecomonomer content of less than 15%, less than 6%, and at least about 2%by weight and 2) propylene/butene copolymers having a majority weight %content of propylene.

EVOH

Ethylene/vinyl alcohol copolymer (“EVOH”) is another usefulthermoplastic. EVOH may have an ethylene content of about 32 mole %, orat least about any of the following values: 20 mole %, 25 mole %, and 30mole %. EVOH may have an ethylene content of below about any of thefollowing values: 50 mole %, 40 mole %, and 33 mole %. As is know in theart, EVOH may be derived by saponifying or hydrolyzing ethylene/vinylacetate copolymers, for example, to a degree of hydrolysis of at leastabout any of the following values: 50%, 85%, and 98%.

Ionomer

Another useful thermoplastic is ionomer, which is a copolymer ofethylene and an ethylenically unsaturated monocarboxylic acid having thecarboxylic acid groups partially neutralized by a metal ion, such assodium or zinc. Useful ionomers include those in which sufficient metalion is present to neutralize from about 10% to about 60% of the acidgroups in the ionomer. The carboxylic acid is preferably “(meth)acrylicacid”—which means acrylic acid and/or methacrylic acid. Useful ionomersinclude those having at least 50 weight % and preferably at least 80weight % ethylene units. Useful ionomers also include those having from1 to 20 weight percent acid units. Useful ionomers are available, forexample, from Dupont Corporation (Wilmington, Del.) under the SURLYNtrademark.

Vinyl Plastics

Useful vinyl plastics include polyvinyl chloride (“PVC”), vinylidenechloride polymer (“PVdC”), and polyvinyl alcohol (“PVOH”). Polyvinylchloride (“PVC”) refers to a vinyl chloride-containing polymer orcopolymer—that is, a polymer that includes at least 50 weight percentmonomer units derived from vinyl chloride (CH₂═CHCl) and also,optionally, one or more comonomer units, for example, derived from vinylacetate. One or more plasticizers may be compounded with PVC to softenthe resin and/or enhance flexibility and processibility. Usefulplasticizers for this purpose are known in the art.

Another exemplary vinyl plastic is vinylidene chloride polymer (“PVdC”),which refers to a vinylidene chloride-containing polymer orcopolymer—that is, a polymer that includes monomer units derived fromvinylidene chloride (CH₂═CCl₂) and also, optionally, monomer unitsderived from one or more of vinyl chloride, styrene, vinyl acetate,acrylonitrile, and C₁-C₁₂ alkyl esters of (meth)acrylic acid (e.g.,methyl acrylate, butyl acrylate, methyl methacrylate). As used herein,“(meth)acrylic acid” refers to both acrylic acid and/or methacrylicacid; and “(meth)acrylate” refers to both acrylate and methacrylate.Examples of PVdC include one or more of the following: vinylidenechloride homopolymer, vinylidene chloride/vinyl chloride copolymer(“VDC/VC”), vinylidene chloride/methyl acrylate copolymer (“VDC/MA”),vinylidene chloride/ethyl acrylate copolymer, vinylidene chloride/ethylmethacrylate copolymer, vinylidene chloride/methyl methacrylatecopolymer, vinylidene chloride/butyl acrylate copolymer, vinylidenechloride/styrene copolymer, vinylidene chloride/acrylonitrile copolymer,and vinylidene chloride/vinyl acetate copolymer.

Useful PVdC includes that having at least about 75, at most about 95,and at most about 98 weight % vinylidene chloride monomer. Useful PVdC(for example, as applied by latex emulsion coating) includes that havingat least about any of 5%, 10%, and 15%—and/or at most about any of 25%,22%, 20%, and 15 weight %—comonomer with the vinylidene chloridemonomer.

A layer that includes PVdC may also include a thermal stabilizer (e.g.,a hydrogen chloride scavenger such as epoxidized soybean oil) and alubricating processing aid (e.g., one or more acrylates).

Polyamide

Useful polyamides include those of the type that may be formed by thepolycondensation of one or more diamines with one or more diacids and/orof the type that may be formed by the polycondensation of one or moreamino acids and/or of the type formed by the ring opening of cycliclactams. Useful polyamides include aliphatic polyamides andaliphatic/aromatic polyamides.

Representative aliphatic diamines for making polyamides include thosehaving the formula:H₂N(CH₂)_(n)NH₂where n has an integer value of 1 to 16. Representative examples includetrimethylenediamine, tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, octamethylenediamine, decamethylenediamine,dodecamethylenediamine, hexadecamethylenediamine. Representativearomatic diamines include p-phenylenediamine, 4,4′-diaminodiphenylether, 4,4′ diaminodiphenyl sulphone, 4,4′-diaminodiphenylethane.Representative alkylated diamines include2,2-dimethylpentamethylenediamine, 2,2,4-trimethylhexamethylenediamine,and 2,4,4 trimethylpentamethylenediamine. Representative cycloaliphaticdiamines include diaminodicyclohexylmethane. Other useful diaminesinclude heptamethylenediamine, nonamethylenediamine, and the like.

Representative diacids for making polyamides include dicarboxylic acids,which may be represented by the general formula:HOOC-Z-COOHwhere Z is representative of a divalent aliphatic or cyclic radicalcontaining at least 2 carbon atoms. Representative examples includealiphatic dicarboxylic acids, such as adipic acid, sebacic acid,octadecanedioic acid, pimelic acid, suberic acid, azelaic acid,dodecanedioic acid, and glutaric acid; and aromatic dicarboxylic acids,such as such as isophthalic acid and terephthalic acid.

The polycondensation reaction product of one or more or the abovediamines with one or more of the above diacids may form usefulpolyamides. Representative polyamides of the type that may be formed bythe polycondensation of one or more diamines with one or more diacidsinclude aliphatic polyamides such as poly(hexamethylene adipamide)(“nylon-6,6”), poly(hexamethylene sebacamide) (“nylon-6,10”),poly(heptamethylene pimelamide) (“nylon-7,7”), poly(octamethylenesuberamide) (“nylon-8,8”), poly(hexamethylene azelamide) (“nylon-6,9”),poly(nonamethylene azelamide) (“nylon-9,9”), poly(decamethyleneazelamide) (“nylon-10,9”), poly(tetramethylenediamine-co-oxalic acid)(“nylon-4,2”), the polyamide of n-dodecanedioic acid andhexamethylenediamine (“nylon-6,12”), the polyamide ofdodecamethylenediamine and n-dodecanedioic acid (“nylon-12,12”).

Representative aliphatic/aromatic polyamides includepoly(tetramethylenediamine-co-isophthalic acid) (“nylon-4,1”),polyhexamethylene isophthalamide (“nylon-6,1”), polyhexamethyleneterephthalamide (“nylon-6,T”), poly (2,2,2-trimethyl hexamethyleneterephthalamide), poly(m-xylylene adipamide) (“nylon-MXD,6”),poly(p-xylylene adipamide), poly(hexamethylene terephthalamide),poly(dodecamethylene terephthalamide), and polyamide-MXD,I.

Representative polyamides of the type that may be formed by thepolycondensation of one or more amino acids include poly(4-aminobutyricacid) (“nylon-4”), poly(6-aminohexanoic acid) (“nylon-6” or“poly(caprolactam)”), poly(7-aminoheptanoic acid) (“nylon-7”),poly(8-aminooctanoic acid) (“nylon-8”), poly(9-aminononanoic acid)(“nylon-9”), poly(10-aminodecanoic acid) (“nylon-10“),poly(11-aminoundecanoic acid) (“nylon-11”), and poly(12-aminododecanoicacid) (“nylon-12” or “poly(lauryllactam)”).

Representative copolyamides include copolymers based on a combination ofthe monomers used to make any of the foregoing polyamides, such as,nylon-4/6, nylon-6/6, nylon-6/9, nylon-6/12, caprolactam/hexamethyleneadipamide copolymer (“nylon-6,6/6”), hexamethylene adipamide/caprolactamcopolymer (“nylon-6/6,6”), trimethylene adipamide/hexamethyleneazelaiamide copolymer (“nylon-trimethyl 6,2/6,2”), hexamethyleneadipamide-hexamethylene-azelaiamide caprolactam copolymer(“nylon-6,6/6,9/6”), hexamethyleneadipamide/hexamethylene-isophthalamide (“nylon-6,6/6,I”), hexamethyleneadipamide/hexamethyleneterephthalamide (“nylon-6,6/6,T”), nylon-6,T/6,I,nylon-6/MXD,T/MXD,I, nylon-6,6/6,10, and nylon-6,1/6,T.

Conventional nomenclature typically lists the major constituent of acopolymer before the slash (“/”) in the name of a copolymer; however, inthis application the constituent listed before the slash is notnecessarily the major constituent unless specifically identified assuch. For example, unless the application specifically notes to thecontrary, “nylon-6/6,6” and “nylon-6,6/6” may be considered as referringto the same type of copolyamide.

Polyamide copolymers may include the most prevalent polymer unit in thecopolymer (e.g., hexamethylene adipamide as a polymer unit in thecopolymer nylon-6,6/6) in mole percentages ranging from any of thefollowing: at least about 50%, at least about 60%, at least about 70%,at least about 80%, and at least about 90%, and the ranges between anyof the forgoing values (e.g., from about 60 to about 80%); and mayinclude the second most prevalent polymer unit in the copolymer (e.g.,caprolactam as a polymer unit in the copolymer nylon-6,6/6) in molepercentages ranging from any of the following: less than about 50%, lessthan about 40%, less than about 30%, less than about 20%, less thanabout 10%, and the ranges between any of the forgoing values (e.g., fromabout 20 to about 40%).

Useful polyamides include those that are approved by the controllingregulating agency (e.g., the U.S. Food and Drug Agency) for eitherdirect contact with food and/or for use in a food packaging film, at thedesired conditions of use.

Polyesters

Useful polyesters include those made by: 1) condensation ofpolyfunctional carboxylic acids with polyfunctional alcohols, 2)polycondensation of hydroxycarboxylic acid, and 3) polymerization ofcyclic esters (e.g., lactone).

Exemplary polyfunctional carboxylic acids (and their derivatives such asanhydrides or simple esters like methyl esters) include aromaticdicarboxylic acids and derivatives (e.g., terephthalic acid, isophthalicacid, dimethyl terephthalate, dimethyl isophthalate) and aliphaticdicarboxylic acids and derivatives (e.g., adipic acid, azelaic acid,sebacic acid, oxalic acid, succinic acid, glutaric acid, dodecanoicdiacid, 1,4-cyclohexane dicarboxylic acid, dimethyl-1,4-cyclohexanedicarboxylate ester, dimethyl adipate). Useful dicarboxylic acids alsoinclude those discussed above in the polyamide section. As is known tothose of skill in the art, polyesters may be produced using anhydridesand esters of polyfunctional carboxylic acids.

Exemplary polyfunctional alcohols include dihydric alcohols (andbisphenols) such as ethylene glycol, 1,2-propanediol, 1,3-propanediol,1,3 butanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol,2,2-dimethyl-1,3-propanediol, 1,6-hexanediol,poly(tetrahydroxy-1,1′-biphenyl, 1,4-hydroquinone, and bisphenol A.

Exemplary hydroxycarboxylic acids and lactones include 4-hydroxybenzoicacid, 6-hydroxy-2-naphthoic acid, pivalolactone, and caprolactone.

Useful polyesters include homopolymers and copolymers. These may bederived from one or more of the constituents discussed above. Exemplarypolyesters include poly(ethylene terephthalate) (“PET”), poly(butyleneterephthalate) (“PBT”), and poly(ethylene naphthalate) (“PEN”). If thepolyester includes a mer unit derived from terephthalic acid, then suchmer content (mole %) of the diacid component of the polyester may be atleast about any the following: 70, 75, 80, 85, 90, and 95%.

The polyester may be thermoplastic. The polyester (e.g., copolyester) ofthe film may be amorphous, or may be partially crystalline(semi-crystalline), such as with a crystallinity of at least about, orat most about, any of the following weight percentages: 10, 15, 20, 25,30, 35, 40,and 50%.

Polystyrene

The matrix medium may comprise polystyrene. Exemplary polysytreneincludes stryrene homo- and co-polymers. Polystyrene may besubstantially atactic, syndiotactic or isotactic. The term “polysytrene”includes copolymer that contains at least 50 mole % monomer unitsderived from styrene. Styrene may be copolymerized with alkyl acrylates,maleic anhydride, isoprene, or butadiene. Styrene copolymers withisoprene and butadiene may be further hydrogenated.

Energy Curable Polymer Precursors

The matrix medium may comprise one or more energy curable polymerprecursors. An energy curable polymer precursor is a compound (e.g.,monomer or oligomer) that is intended for transformation to a curedpolymer by the application of energy in the form of heat and/orradiation (e.g., light), and may also involve an initiator and/orcatalyst. The resulting energy cured polymer may be a thermoset polymeror a thermoplastic polymer. A single energy curable polymer precursormay react to form a polymer, or two or more energy curable polymerprecursors may react together to form a polymer. The energy curablepolymer precursor may be multifunctional, that is, adapted to formcrosslinked polymer when cured. The energy curable chemical reaction maybe induced by heat, catalyst interaction, radiation (e.g., light), ormixing of the energy curable polymer precursors.

Useful energy curable polymer precursors may include one or more of theenergy curable polymer precursors that are precursors to one or more ofthe following polymers: polyester resins (e.g., alkyd resin), allylresins (e.g., diallyl phthalate, diallyl isophtahalate, diallyl maleate,and diallyl chlorendate), amino resins (e.g., urea resins, melamineresins, and their copolymers with formaldehyde), epoxy resins, furanresins, phenolic resins (e.g., phenol-aralkyl resins,phenol-formaldehyde resins), polyacrylic ester resins, polyamide resins,polyurethane resins, polyacrylamide resins, polyimide resins, andacrylamide resins.

Exemplary energy curable polymer precursors may include (meth)acrylates(i.e., methacrylates and/or acrylates), multifunctional (meth)acrylates,thiol-ene systems, and maleimides.

Exemplary energy curable polymer precursors, for example, with respectto polyurethane polymer precursors, may include polyols andpolyisocyanates (e.g., toluene diisocyanate anddiphenyl-methanediisocyanate).

With respect to the polyurethane and epoxy resin precursors, forexample, the intercalated layered silicate may be mixed with the polyolprecursor component rather than the more reactive component to helpminimize premature reaction.

Additional Matrix Medium

The matrix medium may comprise one or more compounds useful in theformulation of one or more of any of the following: coatings (i.e.,paints and/or varnishes), inks, greases, cosmetics, and pharmaceuticaldosage forms.

The matrix medium may comprise one or more materials selected fromcoating (i.e., paint and/or varnish) solvents, coating binders, andcoating resins. Useful coating solvents, coating binders, and coatingresins are known to those of skill in the art; see, for example, thosediscussed in Paints and Coatings, Ullmann's Encyclopedia of IndustrialChemistry, Volume 24, pages 591-790 (2003 Wiley-VCH), of which pages591-790 are incorporated herein by reference. Examples include mineralspirits, toluene, and linseed oil.

The matrix medium may comprise one or more materials selected from inksolvents and ink resins (e.g., ink binders and/or ink vehicles). Usefulink solvents and ink resins are known to those of skill in the art; see,for example, those discussed in Leach and Pierce, The Printing InkManual (5^(th) edition 1993), which is incorporated herein in itsentirety.

The matrix medium may comprise one or more materials selected fromgrease lubricating oils and grease gelling agents. Useful greaselubricating oils and grease gelling agents are known to those of skillin the art; see, for example, those discussed in Kirk-OthmerEncyclopedia of Chemical Technology, Volume 15, pages 493-98 (4^(th)edition 1995), of which pages 493-98 are incorporated herein byreference.

The matrix medium may comprise one or more materials useful in theformulation of cosmetics, for example, one or more materials selectedfrom lipids, emollients, humectants, film formers, binders, surfactants,and solvents. Useful cosmetic lipids, emollients, humectants, filmformers, binders, surfactants, and solvents are known to those of skillin the art; see, for example, those discussed in Kirk-OthmerEncyclopedia of Chemical Technology, Volume 7, pages 572-619 (4^(th)edition 1993), of which pages 572-619 are incorporated herein byreference, and CTFA International Cosmetic Ingredient Handbook, 2^(nd)edition (CTFA Washington D.C. 1992), which is incorporated herein in itsentirety by reference.

Compounds useful in the formulation of pharmaceutical dosage formsinclude pharmaceutical (e.g., medical) excipients (e.g., carriers). Thematrix medium may comprise one or more pharmaceutical excipients, forexample, one or more excipients adapted for an internal pharmaceuticaldosage form and/or adapted for an external pharmaceutical dosage form.Useful pharmaceutical excipients are known to those of skill in the art;see, for example, those discussed in Pharmaceutical Dosage Forms,Ullmann's Encyclopedia of Industrial Chemistry, Volume 25, pages 515-547(2003 Wiley-VCH), of which pages 515-547 are incorporated herein byreference.

The matrix medium may comprise one or more of water, an oil-in-wateremulsion, and a water-in-oil emulsion.

Dispersed Particles

The dispersed particles in the dispersed-particle composition may havean average size of less than about 100 nm in at least one dimension. Theparticles may have an average aspect ratio (i.e., the ratio of theaverage largest dimension to the average smallest dimension of theparticles) of from about 10 to about 30,000. Typically, the aspect ratiofor particles comprising silicate platelets exfoliated from anintercalated layered silicate may be taken as the length (largestdimension) to the thickness (smallest dimension) of the platelets. For aparticle having a fiber configuration, the aspect ratio may be taken asthe length (largest dimension) to the diameter (smallest dimension) ofthe particle.

Useful aspect ratios for the dispersed particles include at least aboutany of the following values: 10; 20; 25; 200; 250; 1,000; 2,000; 3,000;and 5,000; and at most about any of the following values: 25,000;20,000; 15,000; 10,000; 5,000; 3,000; 2,000; 1,000; 250; 200; 25; and20.

The dispersed particles may have an average size in the shortestdimension of at least about any of the following values: 0.5 nm, 0.8 nm,1 nm, 2, nm, 3 nm, 4 nm, and 5 nm; and at most about any of thefollowing values: 100 nm, 60 nm, 30 nm, 20 nm, 10 nm, 8 nm, 5 nm, and 3nm, as estimated from transmission electron microscope (“TEM”) images.The particles may have an average dimension small enough to maintainoptical transparency of the matrix medium in which the particles aredispersed.

The amount of exfoliated particles dispersed in the dispersed-particlecomposition may be at least about any of the following values 0.1, 0.5,1, 1.5, 2, 2.5, 3, 4, 5, and 10 weight %; and/or may be at most aboutany of the following values: 50, 40, 30, 20, 15, 10, 8, 6, 5, 4, 3, 2,and 1 weight %, based on the weight of the dispersed-particlecomposition. Also, the amount of exfoliated particles dispersed in thedispersed-particle composition may be at least about any of thefollowing values: 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, and 10 weightparts; and/or may be at most about any of the following values: 100, 80,60, 50, 40, 30, 20, 15, 10, 8, 6, 5, 4, 3, 2, and 1 weight parts, basedon 100 weight parts of matrix medium, for example, based on 100 weightparts of the one or more polymers discussed above.

The dispersed-particle composition may comprise at least about any ofthe following: 50, 60, 70, 80, 90, 95, and 98 weight %; and at mostabout any of the following: 99, 98, 95, 90, 80, 70, and 60 weight %,based on the weight of the dispersed-particle composition of any of thefollowing: 1) the matrix medium, or 2) the one or more polymers, or 3)the energy curable polymer precursors, or 4) the coating solvents,coating binders, or coating resins, or 5) the ink solvents or inkresins, or 6) the grease lubricating oils or grease gelling agents, or7) the cosmetic lipids, cosmetic emollients, cosmetic humectants,cosmetic film formers, cosmetic binders, cosmetic surfactants, orcosmetic solvents, or 8) pharmaceutical excipients.

The particles may comprise silicate platelets derived from theintercalated layered silicate and an intercalating agent sorbed to thesilicate platelets. Exemplary intercalating agents are discussed above.The dispersed-particle composition may be essentially free ofintercalating agent comprising onium functionality, such as any one, orof all, or of any combination of the onium compounds discussed above.

The amount of intercalating agent sorbed to the silicate platelets maybe at least about and/or at most about any of the following: 1, 5, 10,20, 30, 50, 70, 90, 110, 150, 200, and 300 weight parts per 100 weightparts silicate platelets.

It is believed that exfoliated particles result when individual silicatelayers of a layered silicate are no longer close enough to interactsignificantly with the adjacent layers via ionic or van der Waalsattractions or to form strongly correlated systems due to the largeaspect ratios of the platelets. An exfoliated layered silicate has lostits registry and may be relatively uniformly and randomly dispersed in acontinuous matrix medium. It is believed that the dispersion in a matrixmedium occurs when the interlayer spacing of the layered silicate is ator greater than the average radius of gyration of the moleculescomprising the matrix medium.

A dispersing aid may be used to enhance exfoliation of the intercalatedlayered silicate into the matrix medium. Exemplary dispersing aids mayinclude one or more of water, alcohols, ketones, aldehydes, chlorinatedsolvents, hydrocarbon solvents, and aromatic solvents.

Manufacture of the Dispersed-Particle Composition

The intercalated layered silicate may be exfoliated in a matrix mediumto form the dispersed-particle composition. The intercalated layeredsilicate may be added to the matrix medium under conditions effective toexfoliate at least a portion of the intercalated layered silicate intoparticles comprising silicate platelets dispersed in the matrix medium.An amount of intercalated layered silicate mixed with the matrix mediummay be at least about any of the following: 0.1, 0.5, 1, 1.5, 2, 2.5, 3,4, 5, and 10 weight parts intercalated layered silicate; and/or may beat most about any of the following values: 100, 80, 60, 50, 40, 30, 20,15, 10, 8, 6, 5, 4, 3, 2, and 1 weight parts intercalated layeredsilicate, based on 100 weight parts of matrix medium, for example, basedon 100 weight parts of the one or more polymers discussed above.

At least about any of the following amounts of the intercalated layeredsilicate added to the matrix medium may be dispersed as exfoliatedparticles having an average size of less than about 100 nm in at leastone dimension: 50, 60, 70, 80, 90, 95, 98, and 99 weight partsexfoliated particles per 100 weight parts added intercalated layeredsilicate. The exfoliated silicate platelets may have the averagethickness of the individual layers of the layered silicate, or may haveas an average thickness multiples of less than about any of 10, 5, and 3layers of the layered silicate. TEM images may be used to estimate theamount and size and characteristics of the exfoliated particles.

The effective exfoliation conditions may include the addition of mixingand/or shearing energy to the mixture of the intercalated layeredsilicate and the matrix medium. The process variables for exfoliatingthe intercalated layered silicate in the matrix medium include time,temperature, geometry of the mixing apparatus, and the shear rate, andgenerally requires a balance of these variables, as is known to those ofskill in the art. The balancing of these variables may take into accountthe desire to minimize the physical degradation or decomposition of thematrix medium and/or the intercalating agent, for example, by limitingthe upper temperature of the processing and/or the amount of time at aselected temperature during processing.

An increase in temperature generally provides more thermal energy toenhance exfoliation. A decrease in temperature may lower the viscosityof the mixture while increasing the shear rate. An increase in shearrate generally enhances exfoliation. Shear rates of at least about anyof the following may be applied to the mixture of the intercalatedlayered silicate and the matrix medium: 1 sec⁻¹, 10 sec⁻¹, 50 sect1, 100sec⁻¹, and 300 sec⁻¹.

Illustrative methods or systems for applying shear to effect exfoliationof the intercalated layered silicate in the matrix medium includemechanical systems, thermal shock, pressure alternation, andultrasonics. A flowable mixture may be sheared by mechanical methods,such as the use of stirrers, blenders, Banbury type mixers, Brabendertype mixers, long continuous mixers, injection molding machines, andextruders. Twin screw extruders may be useful, for example, for mixingthe intercalated layered silicate with a thermoplastic matrix medium. Athermal shock method achieves shearing by alternatively raising andlowering the temperature of the mixture to cause thermal expansions andcontractions to induce internal stresses that cause shear. Sudden andalternating pressure changes may also be used to apply shear to themixture. Ultrasonic methods induce shear by cavitation or resonantvibrations, which cause varying portions of the mixture to vibrate andbecome excited at different phases.

The effective exfoliation conditions may comprise raising thetemperature of the matrix medium, for example a matrix medium comprisingone or more thermoplastic polymers, so that the matrix medium isthermally processible at a reasonable rate in the mechanical systemeither before, while, or after adding the intercalated layered silicateto the matrix medium. During processing, the mixture of the intercalatedlayered silicate and the matrix medium may be at a temperature, forexample, of at least about and/or at most about any of the followingtemperatures: 100° C., 150° C., 200° C., 240° C., 280° C., 300° C., 320°C., 350° C., 380° C., and 400° C. The amount of residence time that themixture of the intercalated layered silicate and the matrix medium mayreside at any of these temperatures may be at least about and/or at mostabout any of the following times: 2, 4, 5, 8, 10, 12, 15, and 20minutes.

Before effecting exfoliation, the layered silicate may be reduced insize by methods known in the art, including, but not limited to,grinding, pulverizing, hammer milling, jet milling, and theircombinations, so that the average particle diameter of the layeredsilicate may be, for example, less than about any of 100, 50, and 20microns.

Use of the Intercalated Layered Silicate and Dispersed-ParticleComposition

The dispersed particles may be used to enhance the physical and/orperformance properties of the matrix medium in which they are dispersed.For example, the dispersed particles may improve one or more of themodulus, strength, permeability, rheological, and surface adhesionproperties of the matrix medium incorporating the particles relative tothe matrix medium without the particles.

Several types of products may benefit from incorporation of thedispersed-particle composition to improve, for example, performanceproperties. Exemplary products that may comprise the dispersed-particlecomposition include:

sheets and panels, which, for example, may be further shaped bypressing, molding, and/or thermoforming to form useful objects;

coatings (i.e., paints and/or varnishes);

lubricants, for example, food-grade lubricants;

greases;

personal care products, such as cosmetics (e.g., antiperspirants,deodorants, facial makeup, decorative makeup, toothpastes, shampoos,soaps, skin conditioners, skin moisturizers, and sunscreens);

pharmaceuticals, such as topical medicinal compositions (e.g.,anti-fungal compositions, anti-bacterial compositions, anesthetics,anti-inflammatory compositions, pain-relief ointments, andrash/itch/irritation ointments) and internal medicinal compositions(e.g., pills, tablets, capsules, powders, and solutions); and

packaging materials, such as packaging films (e.g., shrink films,stretch films, and food packaging films), bottles, trays, andcontainers.

A packaging film may comprise one or more layers comprising any of thedispersed-particle compositions discussed above. The film may have anytotal thickness as long as it provides the desired properties (e.g.,free shrink, shrink tension, flexibility, Young's modulus, optics,strength, barrier) for the given application of expected use. The filmmay have a thickness of less than about any of the following: 20 mils,10 mils, 5 mils, 4 mils, 3 mils, 2 mils, 1.5 mils, 1.2 mils, and 1 mil.The film may also have a thickness of at least about any of thefollowing: 0.25 mils, 0.3 mils, 0.35 mils, 0.4 mils, 0.45 mils, 0.5mils, 0.6 mils, 0.75 mils, 0.8 mils, 0.9 mils, 1 mil, 1.2 mils, 1.4mils, 1.5 mils, 2 mils, 3 mils, and 5 mils.

The film may be monolayer or multilayer. The film may comprise at leastany of the following number of layers: 1, 2, 3, 4, 5, 6, 7, 8, and 9.The film may comprise at most any of the following number of layers: 20,15, 10, 9, 7, 5, 3, 2, and 1. The term “layer” refers to a discrete filmcomponent which is coextensive with the film and has a substantiallyuniform composition. Any of the layers of the film may have a thicknessof at least about any of the following: 0.05, 0.1, 0.2, 0.5, 1, 2, and 3mil. Any of the layers of the film may have a thickness of at most aboutany of the following:. 20, 10, 5, 2, 1, and 0.5 mils. Any of the layersof the film may have a thickness as a percentage of the total thicknessof the film of at least about any of the following values: 1, 3, 5, 7,10, 15, 20, 30, 40, 50, 60, 70, 80, and 90%. Any of the layers of thefilm may have a thickness as a percentage of the total thickness of thefilm of at most about any of the following values: 90, 80, 50, 40, 35,30, 25, 20, 15, 10, and 5%.

A layer of the film may comprise at least about and/or at most about anyof the following amounts of dispersed-particle composition based on thelayer weight: 0.1, 0.5, 1, 3, 5, 10, 20, 50, 60, 70, 80, 90, 95, 99, and100 weight %. A layer of the film comprising any of the foregoingamounts of dispersed-particle composition may also have a thickness ofat least about, and/or at most about, any of the following percentagesbased on the total thickness of the film: 90, 80, 70, 60, 50, 40, 30,20, 15, 10, and 5%.

A layer comprising the dispersed-particle composition may be an outerlayer of the film. An outer layer may be an “outside layer” of the film(i.e., an outer layer adapted or designed to face to the outside of apackage incorporating the film) or an “inside layer” of the film (i.e.,an outer layer adapted or designed to face the inside of a packageincorporating the film). If the film comprises only one layer, then theone layer may be considered an “outer layer.” A layer comprising thedispersed-particle composition may be an inner or interior layer of thefilm. An inner or interior layer of the film is between two outer layersof the film.

For example, an internal tie layer of a film, such as disclosed in U.S.patent application Ser. No. 10/452892 filed Jun. 2, 2003 by Grah et al,which is incorporated herein in its entirety by reference, may comprisethe dispersed-particle composition discussed above.

The film comprising the dispersed-particle composition may be formedinto a package (e.g., bag or casing) for packaging (e.g., enclosing) anobject such as a food product (e.g., coffee, nuts, snack foods, cheese,ground or processed meat products, fresh red meat products, and morespecifically, meats such as poultry, pork, beef, sausage, lamb, goat,horse, and fish).

The package may be formed by sealing the film to itself, or by sealingthe film to a support member (e.g., a tray, cup, or tub), which supportsthe product (e.g., a food product) that may be disposed on or in thesupport member. Seals may be made by adhesive or heat sealing, such asbar, impulse, radio frequency (“RF”) or dielectric sealing. Suitablepackage configurations include end-seal bag, side-seal bag, L-seal bag,pouch, and seamed casing (e.g., back-seamed tubes by forming an overlapor fin-type seal). Such configurations are known to those of skill inthe art. The support member (e.g., tray) may also comprise any of thedispersed-particle compositions discussed above. The support member mayalso comprise a thermoformed web comprising a thermoplastic.

The package may also be formed by laminating or sealing the filmcomprising the dispersed-particle composition to another substrate.Suitable substrates may comprise: 1) a film comprising one or more ofthe following materials: polyester (e.g., PET), metalized polyester(e.g., metalized PET), PVdC-coated PET, polypropylene (e.g., biaxiallyoriented polypropylene or BOPP), metalized BOPP, PVdC, and coated BOPP,2) paper, 3) paperboard, and 4) metal foil. A composite packagingstructure may also be formed by extrusion coating of one or more polymerlayers, any or all of which may comprise the dispersed-particlecomposition, to any of the above substrates.

Also by way of example, once a film comprising the dispersed-particlecomposition has been placed in a tube or casing configuration, one endof the tube may be closed by tying, clipping (e.g., metal clips), orsealing. The tube may then be filled through the remaining open end withan uncooked food product (e.g., a sausage emulsion or another flowablemeat product). The remaining open end may then be closed by tying,clipping, or sealing to form a package enclosing a food product. Thisfilling procedure may take place, for example, by verticalform-fill-seal or horizontal form-fill-seal processes known to those ofskill in the art.

The packaged food product enclosed within the package comprising thefilm comprising the dispersed-particle composition may be processed(e.g., cooked, retorted, or pasteurized) for example, by immersing thepackaged food in a liquid hot water bath, exposing the packaged food tosteam, or exposing the packaged food to hot air, for an effective amountof time and at an effective temperature and pressure. This exposure mayalso shrink the package tightly about the enclosed food product by heatshrinking the film. The packaged food may also be exposed to an amountof radiation such as microwave radiation effective to cook the packagedfood. After the food product has been processed (e.g., cooked orretorted) to a desired level, the packaged food may be sold in thepackaged form, or the package may be stripped from the cooked food sothe food may be processed further or consumed.

A film comprising the dispersed-particle composition may be manufacturedby thermoplastic film-forming processes known in the art. The film maybe prepared by extrusion or coextrusion utilizing, for example, atubular trapped bubble film process or a flat film (i.e., cast film orslit die) process. The film may also be prepared by extrusion coating.Alternatively, the film may be prepared by adhesively or extrusionlaminating the various layers. These processes are known to those ofskill in the art. A combination of these processes may also be employed.

A film comprising the dispersed-particle composition may benon-oriented. Alternatively, a film comprising the dispersed-particlecomposition may be oriented in either the machine (i.e., longitudinal),the transverse direction, or in both directions (i.e., biaxiallyoriented), in order to reduce the permeability and/or to enhance thestrength, optics, and durability of the film. The orientation of thefilm may also enhance the orientation of the silicate platelets of thedispersed-particle composition, so that generally the major planethrough the platelets is substantially parallel to the major planethrough the film. The film may be oriented in at least one direction byat least about any of the following ratios: 2.5:1, 3:1, 3.5:1, and3.7:1; and/or by at most about 10:1.

A film comprising the dispersed-particle composition may be non-heatshrinkable—for example, having a free shrink in any direction at 185° F.(85° C.) of less than about any of the following: 4%, 3%, 1%, and 0.5%.A film comprising the dispersed-particle composition may be heatshrinkable (i.e., has a shrink characteristic), which as used herein,means that the film has a free shrink at 185° F. (85° C.) in at leastone direction of at least about 5% at 185° F. For example, filmcomprising the dispersed-particle composition may have a free shrink at185° F. (85° C.) in either of the machine or transverse directions (orboth directions) of at least about, and/or at most about, any of thefollowing: 7%, 10%, 15%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 70%, and80%. Further, the film may have any of the preceding free shrink valuesmeasured at a temperature selected from any of 200° F., 220° F., 240°F., 260° F., and 280° F.

The film may have unequal free shrink in both directions, that isdiffering free shrink in the machine and transverse directions. Forexample, the film may have a free shrink (185° F.) in the machinedirection of at least 40% and a free shrink (185° F.) in the transversedirection of at least 25%. The film may not have a heat shrinkcharacteristic in both directions. For example, the film may have a freeshrink at 185° F. in one direction of less than about any of thefollowing: 5%, 4%, 3%, 2% and 1%; or the film may have 0% free shrink at185° F. in one direction. The free shrink of the film is determined bymeasuring the percent dimensional change in a 10 cm×10 cm film specimenwhen subjected to selected heat (i.e., at a specified temperatureexposure) according to ASTM D 2732, which is incorporated herein in itsentirety by reference. All references to free shrink in this applicationare measured according to this standard.

As is known in the art, a heat-shrinkable film shrinks upon theapplication of heat while the film is in an unrestrained state. If thefilm is restrained from shrinking to some extent—for example by apackaged product around which the film shrinks—then the tension of theheat-shrinkable film increases upon the application of heat.Accordingly, a heat-shrinkable film that has been exposed to heat sothat at least a portion of the film is either reduced in size(unrestrained) or under increased tension (restrained) is considered aheat-shrunk (i.e., heat-contracted) film.

A film comprising the dispersed-particle composition may exhibit ashrink tension at 185° F. in at least one direction of at least about,and/or at most about, any of the following: 100 psi, 150 psi, 175 psi,200 psi, 225 psi, 250 psi, 275 psi, 300 psi, 325 psi, 350 psi, 400 psi,450 psi, 500 psi, 550 psi, and 600 psi. Further, the film may have anyof the preceding shrink tensions measured at a temperature selected fromany of 200° F., 220° F., 240° F., 260° F., and 280° F. The film may haveunequal shrink tension in both directions, that is differing shrinktension in the machine and transverse directions. The film may not havea shrink tension in one or both directions. Shrink tension is measuredat a specified temperature (e.g., 185° F.) in accordance with ASTM D2838 (Procedure A), which is incorporated herein in its entirety byreference. All references to shrink tension in this application are bythis standard.

A film comprising the dispersed-particle composition may be annealed orheat-set to reduce the free shrink slightly, substantially, orcompletely; or the film may not be heat set or annealed once theoriented film has been quenched in order that the film will have a highlevel of heat shrinkability.

Appearance Characteristics

A film comprising the dispersed-particle composition may have low hazecharacteristics. Haze is a measurement of the transmitted lightscattered more than 2.5° from the axis of the incident light. Haze ismeasured against the outside layer of the film. As previously discussed,the “outside layer” is the outer layer of the film that will be adjacentthe area outside of the package comprising the film. Haze is measuredaccording to the method of ASTM D 1003, which is incorporated herein inits entirety by reference. All references to “haze” values in thisapplication are by this standard. The haze of the film may be no morethan about any of the following values: 30%, 25%, 20%, 15%, 10%, 8%, 5%,and 3%.

A film comprising the dispersed-particle composition may have a gloss,as measured against the outside layer of at least about any of thefollowing values: 40%, 50%, 60%, 63%, 65%, 70%, 75%, 80%, 85%, 90%, and95%. These percentages represent the ratio of light reflected from thesample to the original amount of light striking the sample at thedesignated angle. All references to “gloss” values in this applicationare in accordance with ASTM D 2457 (60° angle), which is incorporatedherein in its entirety by reference.

A film comprising the dispersed-particle composition may be transparent(at least in the non-printed regions) so that a packaged article may bevisible through the film. “Transparent” means that the film transmitsincident light with negligible scattering and little absorption,enabling objects (e.g., the packaged article or print) to be seenclearly through the film under typical viewing conditions (i.e., theexpected use conditions of the material). The transparency (i.e.,clarity) of the film may be at least about any of the following values:65%, 70%, 75%, 80%, 85%, and 90%, as measured in accordance with ASTM DI746.

The measurement of optical properties of plastic films, including themeasurement of total transmission, haze, clarity, and gloss, isdiscussed in detail in Pike, LeRoy, “Optical Properties of PackagingMaterials,” Journal of Plastic Film & Sheeting, vol. 9, no. 3, pp.173-80 (July 1993), of which pages 173-80 is incorporated herein byreference.

The following examples are presented for the purpose of furtherillustrating and explaining the present invention and are not to betaken as limiting in any regard. Unless otherwise indicated, all partsand percentages are by weight.

EXAMPLE 1

10.0 grams of montmorillonite (Cloisite Na+, Southern Clay Products) wasmixed with 10 grams of water in a standard Coors mortar to form aclay/water slurry at room temperature. 3.83 grams (95 meq/100 g clay) ofthe intercalating agent pentaerythritol monostearate (PEMS) from OleonCorporation under the Radiasurf 7174 trademark was heated to 100° C.using a double boiler and then added to the slurry. The resultingmixture was hand compounded in the mortar for 10 minutes at roomtemperature to form an intercalated layered silicate, namely, a PEMSintercalated montmorillonite clay. The intercalated layered silicate wasdried in an 80° C. oven overnight, ground, and sieved through a 325 meshscreen to a fine powder.

The average interlayer spacing (i.e., the basal d-spacing) of theresulting intercalated layered silicate (i.e., PEMS intercalated clay)was determined using a BEDE D1 X-ray diffractometer. A representativesample of the PEMS intercalated clay was set upon a fritted glass slidefor scanning by the diffractometer, which was operated in the powderdiffraction mode using a copper X-ray source (X-ray wave-length 0.154nm) and a sweep of 0.5 to 20 2Theta-Omega. The interlayer spacing wascalculated using Bragg's Law, nλ=2*d sin θ, where “n”=the order of thediffraction peak, “λ”=the wavelength, “d”=the interlayer spacing (i.e.,the basal d-spacing), and “θ”=the scattering angle. The diffractionpattern for the PEMS intercalated clay is shown in FIG. 1. The patternindicated a diffraction peak or shoulder at a 2θ of from 1.22° to 1.30°,which calculates to an average interlayer spacing of the layeredsilicate (i.e., the primary basal d-spacing) of from 68 to 72 Å.

FIG. 2 shows the diffraction pattern for the non-intercalatedmontmorillonite clay. The pattern indicated a diffraction peak at a 2θof 7.42°, which calculates to an average interlayer spacing (i.e., theprimary basal d-spacing) for the montmorillonite clay beforeintercalation of 11.9 Å, measured and calculated as set forth above.Accordingly, the inclusion of the PEMS intercalating agent between thesilicate layers of the montmorillonite increased the average interlayerspacing of the silicate layers by from about 56.1 to about 60.1 Å.

Thermogravimetric analysis (TGA) was obtained for the Example 1 PEMSintercalated montmorillonite clay and the Cloisite 20A intercalated claydescribe below as Comparative Sample 1. The TGA equipment used was a TGAQ50 model available from TA Instruments, Inc. operating at a 20° C. perminute scan rate from room temperature to 800° C. in an argon purgedatmosphere. FIG. 8 shows the TGA results for the primary and firstderivative of weight loss for the Example 1 PEMS intercalatedmontmorillonite. FIG. 9 shows the TGA results for the primary and firstderivative weight loss for the Comparative Sample 1. The peakdegradation temperature of the Example 1 PEMS intercalatedmontmorillonite was 399.94° C., which is about 87° C. higher than the312.92° C. peak degradation temperature of the Comparison Sample 1intercalated montmorillonite. Further, the onset temperature ofdegradation for the Example 1 PEMS intercalated montmorillonite wasapproximately 50° C. higher than for the Comparison Sample 1.

EXAMPLE 2

250 grams of montmorillonite (Cloisite Na+, Southern Clay Products) wasmixed with 100 grams of water in a Hobart mixing bowl at roomtemperature to form a clay/water slurry. 95.75 grams of theintercalating agent pentaerythritol monostearate (PEMS) was heated to40° C. and then added to the slurry. The resulting mixture wascompounded using a Hobart auger extruder at room temperature for 30minutes and with a rotor rotation speed of 200 rpm to form anintercalated layered silicate, namely, a PEMS intercalatedmontmorillonite clay. The intercalated clay was dried in an 80° C. ovenovernight, ground, and sieved through a 325 mesh screen to yield a finepowder of the PEMS intercalated montmorillonite.

Comparative Sample 1

A commercially available dimethyl didehydrogenated tallow quaternaryammonium intercalated montmorillonite (Cloisite 20A) was obtained fromSouthern Clay Products. The concentration of the intercalating agent was95 meq/100 g clay. The average interlayer spacing of the intercalatedclay was determined as described above with respect to Example 1. Thediffraction pattern for Cloisite 20A is shown in FIG. 3. The patternindicated a diffraction peak at a 2θ of 3.65°, which calculated to anaverage interlayer spacing of the layered silicate of 24.2 Å.

EXAMPLE 3

The PEMS intercalated clay of Example 1 was mixed with a matrix mediumof linear low density polyethylene (LLDPE) from the Dow Corporationunder the Dowlex 2045 trade name. The ratio of the mixture was 5 weight% PEMS intercalated clay to 95 weight % LLDPE matrix medium. The mixturewas compounded for 45 minutes at 145° C. using a Haake Rheomix 600 BowlMixer operating at 55 rpm mixer speed to form the Example 3dispersed-particle composition. The resulting dispersed-particlecomposition was pressed on a Carver press between two glass plates intoa transparent film having a thickness varying from 40 to 100 microns.

A wide angle X-ray diffraction pattern was obtained for the Example 3dispersed-particle composition using the method described above withrespect to Example 1 and is shown in FIG. 4. The results indicated thatthe intercalated layered silicate was substantially exfoliated becausethe peak or shoulder corresponding to the d-spacing for clayintercalated with PEMS was absent, and the film was substantiallytransparent.

EXAMPLE 4

The PEMS intercalated clay of Example 1 was mixed with a matrix mediumof isotactic polypropylene from ExxonMobil Corporation under theEscorene PP-4292 tradename. The ratio of the mixture was 5 weight % PEMSintercalated clay to 95 weight % polypropylene matrix medium. Themixture was compounded for 45 minutes at 170° C. using a Haake Rheomix600 Bowl Mixer operating at 50 rpm mixer speed to form the Example 4dispersed-particle composition. The resulting dispersed-particlecomposition was pressed on a Carver press between two glass plates intoa transparent film having a thickness varying from 40 to 100 microns.

A wide angle X-ray diffraction pattern was obtained for the Example 4dispersed-particle composition using the method described above withrespect to Example 1 and is shown in FIG. 5. The results indicated thatthe intercalated layered silicate was substantially exfoliated becausethe peak or shoulder at a 2θ of from 1.22° to 1.30° corresponding to thed-spacing for clay intercalated with PEMS was absent, and the film wassubstantially transparent.

EXAMPLE 5

The PEMS intercalated clay of Example 1 was mixed with a matrix mediumof ethylene/vinyl acetate copolymer (EVA) having 28 weight % vinylacetate content from Exxon Chemical Corporation under the EscoreneLD-761 tradename. The ratio of the mixture was 5 weight % PEMSintercalated clay to 95 weight % EVA matrix medium. The mixture wascompounded for 45 minutes at 155° C. using a Haake Rheomix 600 BowlMixer-operating at 60 rpm mixer speed to form the Example 5dispersed-particle composition. The resulting dispersed-particlecomposition was pressed on a Carver press between two glass plates intoa transparent film having a thickness varying from 40 to 100 microns.

A wide angle X-ray diffraction pattern was obtained for the Example 5dispersed-particle composition using the method described above withrespect to Example 1 and is shown in FIG. 6. The results indicated thatthe intercalated layered silicate was substantially exfoliated becausethe peak or shoulder at a 2θ of from 1.22° to 1.30° corresponding to thed-spacing for clay intercalated with PEMS was absent, and the film wassubstantially transparent. It is hypothesized that the 2θ peak at about6° may indicate that some non-intercalated layered silicate might havebeen present, perhaps because the sheer of the mixing and/or thereactivity of the matrix medium may have degraded some of the PEMSintercalating agent to allow collapse of some silicate layers together.

EXAMPLE 6

The PEMS intercalated clay of Example 1 was mixed with a matrix mediumof nylon-6 polymer (PA6) from BASF Corporation under the Ultramid B35tradename. The ratio of the mixture was 5 weight % PEMS intercalatedclay to 95 weight % PA6 matrix medium. The mixture was compounded for 45minutes at 210° C. using a Haake Rheomix 600 Bowl Mixer operating at 50rpm mixer speed to form the Example 6 dispersed-particle composition.The resulting dispersed-particle composition was pressed on a Carverpress between two glass plates into a transparent film having athickness varying from 40 to 100 microns.

A wide angle X-ray diffraction pattern was obtained for the Example 6dispersed-particle composition using the method described above withrespect to Example 1 and is shown in FIG. 7. The results indicated thatthe intercalated layered silicate was substantially exfoliated becausethe peak or shoulder at a 2θ of from 1.22° to 1.30° corresponding to thed-spacing for clay intercalated with PEMS was absent, and the film wassubstantially transparent.

Any numerical value ranges recited herein include all values from thelower value to the upper value in increments of one unit provided thatthere is a separation of at least 2 units between any lower value andany higher value. As an example, if it is stated that the amount of acomponent or a value of a process variable (e.g., temperature, pressure,time) may range from any of 1 to 90, 20 to 80, or 30 to 70, or be any ofat least 1, 20, or 30 and/or at most 90, 80, or 70, then it is intendedthat values such as 15 to 85, 22 to 68, 43 to 51, and 30 to 32, as wellas at least 15, at least 22, and at most 32, are expressly enumerated inthis specification. For values that are less than one, one unit isconsidered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. These areonly examples of what is specifically intended and all possiblecombinations of numerical values between the lowest value and thehighest value enumerated are to be considered to be expressly stated inthis application in a similar manner.

The above descriptions are those of preferred embodiments of theinvention. Various alterations and changes can be made without departingfrom the spirit and broader aspects of the invention as defined in theclaims, which are to be interpreted in accordance with the principles ofpatent law, including the doctrine of equivalents. Except in the claimsand the specific examples, or where otherwise expressly indicated, allnumerical quantities in this description indicating amounts of material,reaction conditions, use conditions, molecular weights, and/or number ofcarbon atoms, and the like, are to be understood as modified by the word“about” in describing the broadest scope of the invention. Any referenceto an item in the disclosure or to an element in the claim in thesingular using the articles “a,” “an,” “the,” or “said” is not to beconstrued as limiting the item or element to the singular unlessexpressly so stated. The definitions and disclosures set forth in thepresent Application control over any inconsistent definitions anddisclosures that may exist in an incorporated reference. All referencesto ASTM tests are to the most recent, currently approved, and publishedversion of the ASTM test identified, as of the priority filing date ofthis application. Each such published ASTM test method is incorporatedherein in its entirety by this reference.

1. An intercalated layered silicate comprising: a layered silicatecomprising a plurality of silicate layers; and an intercalating agentsorbed between the silicate layers in an amount effective to provide anaverage interlayer spacing between the silicate layers of at least about20 Å, wherein the intercalating agent has a formula selected from:

wherein: R⁴ represents any of: 1) an acyl group having at least 8 carbonatoms; 2) an alkyl group having at least 8 carbon atoms; 3) an alkenylgroup having at least 8 carbon atoms; 4) an alkadienyl group having atleast 8 carbon atoms; and 5) a carbon chain group having at least 8carbon atoms, wherein the carbon chain group incorporates one or morependant or terminal groups selected from hydroxyl, carboxyl, epoxy,isocyanate, aryl, and arylmethyl, wherein the arylmethyl group has theformula

wherein “Ar” represents an aryl group, and R⁶ and R⁷ independentlyrepresent hydrogen, an acyl group, an alkyl group, or an alkenyl group;R⁵represents H, —CH₃, —CH₂CH₃, or any of the groups represented by R⁴;R⁸ represents an oxylated group having a formula selected from:

wherein “n” ranges from 2 to 12 and “x” ranges from 4 to 14; and R¹, R²,and R³ each independently represents H, —CH₃, —CH₂CH₃,

or any of the groups represented by R⁴ and R⁸, provided that at leasttwo R¹, R², and R³ is H.
 2. The intercalated layered silicate of claim 1wherein the intercalating agent has the formula I.
 3. The intercalatedlayered silicate of claim 1 wherein the intercalating agent has theformula II.
 4. The intercalated layered silicate of claim 1 wherein theintercalating agent has the formula II.
 5. The intercalated layeredsilicate of claim 1 wherein the intercalating agent has the formula IV.6. The intercalated layered silicate of claim 1 wherein theintercalating agent has the formula V.
 7. The intercalated layeredsilicate of claim 1 wherein the intercalating agent has the formula Vand R⁸ represents an oxylated group having a formula selected from:


8. The intercalated layered silicate of claim 1 wherein theintercalating agent has the formula VI.
 9. The intercalated layeredsilicate of claim 1 wherein the intercalating agent has the formula VII.10. The intercalated layered silicate of claim 1 wherein R⁴ is branched.11. The intercalated layered silicate of claim 1 wherein R⁴ isunbranched.
 12. The intercalated layered silicate of claim 1 wherein R⁴is an acyl group.
 13. The intercalated layered silicate of claim 1wherein R⁴ is an alkyl group.
 14. The intercalated layered silicate ofclaim 1 wherein each of R¹, R², and R³ is a hydrogen.
 15. Theintercalated layered silicate of claim 1 wherein the intercalating agentcomprises an ester of pentaerythritol.
 16. The intercalated layeredsilicate of claim 1 wherein the intercalating agent comprises a fattyacid ester of pentaerythritol.
 17. The intercalated layered silicate ofclaim 1 wherein the intercalating agent comprises pentaerythritolmonostearate.
 18. The intercalated layered silicate of claim 1 whereinthe intercalating agent comprises an ester of citric acid.
 19. Theintercalated layered silicate of claim 1 wherein the intercalating agentcomprises a fatty acid ester of citric acid.
 20. The intercalatedlayered silicate of claim 1 wherein the intercalating agent comprisesstearyl citrate.
 21. The intercalated layered silicate of claim 1wherein the intercalated layered silicate is essentially free of anintercalating agent comprising an ammonium compound.
 22. Theintercalated layered silicate of claim 1 wherein the intercalatedlayered silicate is essentially free of an intercalating agentcomprising onium functionality.
 23. The intercalated layered silicate ofclaim 1 wherein the amount of sorbed intercalating agent is at leastabout 5 weight parts per 100 weight parts layered silicate.
 24. Theintercalated layered silicate of claim 1 wherein the average interlayerspacing between the silicate layers is at least about 30 Å.
 25. Theintercalated layered silicate of claim 1 wherein the layered silicate isa bentonite clay.
 26. The intercalated layered silicate of claim 1having a peak degradation temperature of at least about 360° C.
 27. Amethod of exfoliating a layered silicate comprising: mixing from about0.1 to about 100 weight parts of the intercalated layered silicate ofclaim 1 with 100 weight parts of a matrix medium to form a mixture; andadding sufficient energy to the mixture to form a dispersed-particlecomposition comprising at least about 0.1 weight parts exfoliatedparticles per 100 weight parts matrix medium.
 28. The method of claim 27wherein the exfoliated particles have an average dimension in theshortest dimension of at most about 100 nm.
 29. The method of claim 27wherein the matrix medium comprises one or more polymers selected frompolyolefin, ethylene/vinyl alcohol copolymer, ionomer, vinyl plastic,polyamide, polyester, and polystyrene.
 30. The method of claim 27wherein the matrix medium comprises one or more energy curable polymerprecursors.
 31. The method of claim 27 wherein the matrix mediumcomprises one or more materials selected from coating solvents, coatingbinders, and coating resins.
 32. The method of claim 27 wherein thematrix medium comprises one or more materials selected from ink solventsand ink resins.
 33. The method of claim 27 wherein the matrix mediumcomprises one or more materials selected from grease lubricating oilsand grease gelling agents.
 34. The method of claim 27 wherein the matrixmedium comprises one or more materials selected from cosmetic lipids,cosmetic emollients, cosmetic humectants, cosmetic film formers,cosmetic binders, cosmetic surfactants, and cosmetic solvents.
 35. Themethod of claim 27 wherein the matrix medium comprises one or morepharmaceutical excipients.
 36. The method of claim 27 wherein the matrixmedium comprises an emulsion selected from an oil-in-water emulsion anda water-in-oil emulsion.
 37. The method of claim 27 comprising mixingfrom about 1 to about 10 weight parts of the intercalated layeredsilicate of claim 1 with 100 weight parts of a matrix medium.
 38. Themethod of claim 27 comprising adding sufficient energy to the mixture toform a dispersed-particle composition comprising at least about 1 weightparts exfoliated particles per 100 weight parts matrix medium.
 39. Adispersed-particle composition comprising: at least about 50 weight % ofa matrix medium; and from at least about 0.1 to at most about 50 weight% of particles dispersed in the matrix medium, the particles having anaverage size in the shortest dimension of at most about 100 nm, theparticles comprising: silicate platelets; and an intercalating agentsorbed to the silicate platelets, the intercalating agent having aformula selected from formulas I through VII of claim
 1. 40. Thedispersed-particle composition of claim 39 wherein the matrix mediumcomprises one or more polymers selected from polyolefin, ethylene/vinylalcohol copolymer, ionomer, vinyl plastic, polyamide, polyester, andpolystyrene.
 41. A packaged food comprising: a package comprising thedispersed-particle composition of claim 39; and a food enclosed in thepackage.
 42. A packaging film comprising the dispersed-particlecomposition of claim 39, wherein the matrix medium comprises one or morepolymers, wherein the one or more polymers are thermoplastic.
 43. Amethod of packaging a food comprising: enclosing a food in a packagecomprising the packaging film of claim 42.